Subfloor repairs in Victoria

Subfloor repairs fix the stumps, bearers and joists under a suspended timber floor, including damage from damp, poor ventilation and termites. In Victoria, re-stumping, re-blocking and structural work must be done by a registered builder, and replacing footings or supporting parts generally needs a building permit. Dwellix, a registered domestic builder (CDB-U 102264), coordinates and delivers subfloor repairs with suitably qualified contractors, and external engineers where required.

Key facts

Registered builder: structural work needs one, whatever its cost, and owner-builders can’t do subfloor work. (Consumer Affairs Victoria; Building and Plumbing Commission)

Building permit: the repair exemption doesn’t cover underpinning, replacing footings or altering a part that supports another part. (Building Regulations 2018)

Ventilation: the National Construction Code requires ventilation openings and ground clearance under suspended floors. (Australian Building Codes Board)

Damp: ground moisture in a subfloor can create a damp environment that encourages timber rot, fungus growth and the potential for termite activity. (Australian Building Codes Board)

Rentals: damp or mould caused by the building structure that makes a home unsafe to live in is an urgent repair. (Consumer Affairs Victoria)

Checked 8 October 2026.

What do subfloor repairs cover?

Repairs to the structure under a suspended timber floor, and to the conditions that damage it:

stumps or piers;
bearers and joists, including members damaged by rot or termites;
damaged flooring;
subfloor ventilation and damp under the house.

The Building Regulations 2018 describe the restumping and reblocking class of building work as sub-floor works and the levelling and supporting of existing structures, and the Building and Plumbing Commission (BPC) lists replacing defective subfloor members and flooring among the experience needed for that class.

Related work has its own pages: restumping for replacing the stumps under a house, floor levelling for sloping or uneven floors, and structural rectification for cracks, foundation movement and your rights if building work is defective. We don’t take over or finish another builder’s incomplete project.

Sources: Building Regulations 2018, Schedule 12; Building and Plumbing Commission, “What is domestic building work?”. Checked 8 October 2026.

Do subfloor repairs need a building permit?

It depends on what’s repaired, and your building surveyor confirms. Under Schedule 3 of the Building Regulations 2018, the repair, renewal or maintenance of part of an existing building is exempt from a building permit only if the work:

won’t adversely affect the building’s structural soundness;
doesn’t increase or decrease its floor area or height;
doesn’t involve underpinning or replacing footings;
doesn’t remove or alter a part of the building that supports another part;
uses materials commonly used for the same purpose as those being replaced;
won’t adversely affect safety or an essential safety measure.

So the answer turns on whether the repair touches the footings, or a part that supports another part. The City of Monash, for example, treats re-stumping as a structural alteration to a building’s footings that needs a building permit. Even exempt work can need a planning permit: in a Heritage Overlay, for example, where it changes your home’s appearance or uses different materials.

Older homes. When you alter an existing building, the work must comply with the Building Regulations 2018, which adopt the Building Code of Australia. The building surveyor can consent to partial compliance, taking into account the building’s structural adequacy, its amenity, and the safety and health of the people using it, and confirms how current requirements apply to your repairs.

If your project needs a building permit, we handle the permit process for you. You formally appoint the building surveyor, and we can recommend one and manage everything with them. Where structural design is needed, we coordinate a suitably qualified external engineer. Engineering scope, costs and responsibilities are confirmed for each project. See our building permits guide.

Sources: Building Regulations 2018, regulations 10 and 233 and Schedule 3; City of Monash, “Reblocking”; Victoria Planning Provisions, clause 43.01. Checked 8 October 2026.

Who can carry out subfloor repairs?

A registered builder, for anything structural. Consumer Affairs Victoria says re-stumping, re-blocking and structural work must be done by registered building practitioners, and that structural work needs a registered builder whatever its cost. The BPC says owner-builders can’t do subfloor work. The unlimited class that Dwellix holds (CDB-U 102264) covers all components of domestic building work under Schedule 12 of the Building Regulations 2018, while plumbing, gas and electrical work is done by licensed tradespeople. Check any builder’s registration, status and conditions on the BPC’s public register before you sign.

For contracts signed from 1 July 2026, Home Warranty, the BPC’s statutory insurance, applies to eligible domestic building work valued at more than $20,000, including repairs, subject to eligibility, limits and exclusions. For what to agree before work starts, see floor levelling.

Sources: Consumer Affairs Victoria; Building and Plumbing Commission; Building Regulations 2018, Schedule 12. Checked 8 October 2026.

What does the National Construction Code say about subfloor ventilation?

It sets minimum ventilation and clearance under suspended floors. The NCC’s Housing Provisions require a subfloor space to have:

ventilation openings in external walls and internal subfloor walls, sized for the local climatic zone;
a minimum clearance between the ground and the lowest horizontal member in the subfloor;
no building debris, vegetation or dead air spaces;
an extra measure where the ground or subfloor is excessively damp or subject to frequent flooding, such as more ventilation, sealing the ground with an impervious membrane, or more durable or treated framing.

The NCC explains that ground moisture rising into or entering a subfloor can create a damp environment that encourages timber rot, fungus growth and the potential for termite activity, and that ventilation increases air flow and reduces damaging water vapour. These are requirements for building work; your building surveyor confirms how they apply to repairs to an existing home.

Sources: Australian Building Codes Board, “Housing Provisions Standard 2025, Part 6.2” and “NCC 2025 state and territory adoption information”; Building Regulations 2018, regulations 10 and 233. Checked 8 October 2026.

What about termites?

Victorian councils may designate areas where buildings are likely to be subject to termite attack, and anyone can ask the council whether a property is in one. Under the NCC, a termite management system is required where a house is built in an area where termites are known to present a potential risk of attack and a primary building element is susceptible. The NCC notes that termites are a lesser risk in parts of Victoria, and that the relevant authority may have records of termite activity.

Your building surveyor confirms what termite protection a building permit requires. In Greater Geelong, for example, the City says to make sure the building permit for a property in a designated termite area includes the required treatments.

Sources: Building Regulations 2018, regulations 51 and 150; Australian Building Codes Board, Housing Provisions Standard 2025, Part 3.4; City of Greater Geelong, “Building permits”. Checked 8 October 2026.

Repairing termite-damaged subfloor timber

Deal with the termites before the timber. If termites may still be active, we recommend having a pest management professional inspect and, where needed, treat them before repairs start. We can arrange a pest management professional, or you’re welcome to use your own. We then assess how far the damage goes in the stumps, bearers, joists and flooring, and replace or strengthen members as the scope or the external engineer’s design requires. We also look for what drew the termites in, such as damp ground, leaks or timber in contact with soil, so the repair doesn’t leave the same conditions behind.

Subfloor damp or termites in a rental property

Consumer Affairs Victoria says pests, infestations, mould and damp can harm people’s health and damage property, and lists termites among pests. Renters who see signs of pests, mould or rising damp should tell the rental provider immediately. Where pests, mould or damp caused by or related to the building structure make the property unsafe or insecure to live in, they’re an urgent repair. The rental provider may be responsible where a problem with the property caused them and hasn’t been fixed. If the renter and rental provider can’t agree who pays, either can apply to VCAT.

Rental properties must also meet minimum standards, including being structurally sound and free from mould and damp caused by or related to the building structure. See investment property renovations.

Sources: Consumer Affairs Victoria, “Pests, infestations and mould” (updated 23 April 2025) and “Rental properties – minimum standards”. Checked 8 October 2026.

Could subfloor repairs disturb asbestos?

They may, in a home built before 1990. WorkSafe Victoria says asbestos-containing materials are very common in buildings built before 1990, and lists walls and vinyl flooring among common locations. Only laboratory testing confirms asbestos. We engage licensed asbestos removalists where required.

Source: WorkSafe Victoria. Checked 8 October 2026.

How we approach subfloor repairs

Damp, blocked ventilation and termites can affect several members, so our inspection is a visual check of the parts of the subfloor that can be seen and safely accessed. We look for:

the stumps, bearers, joists and flooring;
moisture under the house and its likely source, such as leaking plumbing, downpipes or poor drainage;
whether vents are blocked and the ground under the house is clear;
signs of termite activity or past damage.

Some problems can’t be seen until work starts, and these are dealt with as they’re found.

Depending on what we find, repairs may involve replacing or adding stumps, replacing or strengthening damaged bearers and joists, replacing affected flooring, and improving ventilation or drainage so the problem is less likely to return. Where structural design is needed, the external engineer specifies the repair before work starts.

How a Dwellix renovation runs

Send us your address and we’ll confirm whether we can take on your project.

Initial enquiry and consultation.
Site inspection and assessment. For subfloor repairs, this includes the subfloor where it can be safely accessed, plus the signs you’ve noticed.
Detailed scope preparation.
Quotation and client approval.
Contracts, approvals and permits where required. We handle the permit process for you. You formally appoint the building surveyor, and we can recommend one and manage everything with them. We coordinate any engineering design required.
Trade scheduling and procurement.
Construction and project supervision.
Relevant inspections and quality checks.
Practical completion and handover. You receive the compliance certificates for any plumbing and electrical work, the certificate of final inspection where the work has a building permit, and the manufacturer warranties and manuals for what we install.

Frequently asked questions

Do I need a building permit to replace floor joists?

It depends on the work, and your building surveyor confirms. The repair exemption in Schedule 3 of the Building Regulations 2018 doesn’t cover work that adversely affects structural soundness, or that removes or alters a part of the building that supports another part. Structural work also needs a registered builder, whatever its cost.

Who is responsible for rising damp in a rental property?

It depends on the cause. Consumer Affairs Victoria says the rental provider may be responsible where a problem with the property caused the damp and hasn’t been fixed, and that damp caused by or related to the building structure that makes a property unsafe to live in is an urgent repair. If they can’t agree, either party can apply to VCAT.

How do I find out if my property is in a termite area?

Ask your council. Under the Building Regulations 2018, councils may designate areas where buildings are likely to be subject to termite attack, and anyone can ask the council whether a property is in one. Your building surveyor confirms what termite protection a building permit requires.

Do subfloor repairs have to meet current ventilation rules?

When you alter an existing building, the work must comply with the Building Regulations 2018, which adopt the National Construction Code, including its subfloor ventilation requirements. Your building surveyor confirms how these apply to your repairs, and can consent to partial compliance.

How much do subfloor repairs cost?

We don’t publish a set price. The scope depends on how much of the subfloor is affected and why, access under the floor, the permit and any structural design required, and any work on ventilation or flooring. We quote after a site inspection and a detailed scope, so the price reflects your home.

Enquire about subfloor repairs

Enquire and tell us what you’ve noticed under or around your floors. Send us your address and we’ll confirm whether we can take on your project. Prefer email? Write to sales@dwellix.com.au.

General information only, checked 8 October 2026. Rules change; confirm requirements for your property with your building surveyor or council.